Arbitrage Calculator
Enter the odds for each outcome from two different sportsbooks and your total stake. This calculator tells you whether an arb exists, the guaranteed profit %, and exactly how to split your stake so you lock in the same return no matter who wins.
How arbitrage works
An arbitrage — or arb — is a set of bets across the whole market that guarantees a profit whatever the result. It exists when two books disagree enough that their combined prices leave a gap. You measure it by adding up the inverse decimal odds of every outcome.
Take +105 on side A at Book 1 (decimal 2.05) and +110 on side B at Book 2 (decimal 2.10). Inverse odds are 0.4878 and 0.4762, summing to 0.9640 — under 1, so an arb exists. On a $1,000 total you'd stake about $505.98 on A and $494.02 on B, and either result returns roughly $1,037 — a locked 3.73% profit.
Why many sharps skip arbing
Arbs are real, but the profits are thin (usually 1–4%), the windows close fast as lines move, and books quickly limit or ban accounts that arb repeatedly. Because you must bet the full market, your capital is tied up on both sides for a tiny locked edge.
Most disciplined bettors prefer +EV betting: instead of locking in a tiny sure thing, you take just the one side that's mispriced against the fair line. It scales better, ties up less money, and looks far less like arbitrage to the sportsbook.
Curious which side of an arb is the genuinely +EV bet? Devig the sharp line with the no-vig calculator, price it with the EV calculator, and read What Is +EV Betting? for the full case.
Scan for edges without the ban risk.
Iron Marker compares every major US sportsbook against the sharp line in real time and surfaces the +EV bets — the durable version of what arbers chase — with the Kelly stake already set. $39/mo, 7-day free trial.
Start free trialIron Marker is an analytics tool, not a sportsbook, and this calculator is educational — not betting or financial advice. Must be 21+. Problem gambling? Call 1-800-GAMBLER.